Metropolitan Theodosius, head of the million-member Orthodox Church in America, has been designated archbishop of Washington by the church's Sixth All-American Council, meeting in Detroit earlier this month.

The primate, who also retains responsibilities as head of the OCA, is expected to establish a residence here shortly and will commute between here and Syosset, N.Y., where the church's national office is located.

He will replace Bishop Basil Rodzianko, who has been made bishop of San Francisco and the Diocese of the West.

A church representative said the designation of Washington as the seat of the church's primate was made "because Washington, being the capital, would be the normal place to have a local [national] church and since 1970 we consider ourselves as the local [Orthodox] church in the United States."

Orthodox Christianity, which split from Rome in the 11th century, as emerged as national or ethnic churches throughout Eastern Europe and the Middle East. Emigres from those countries to the United States brought with them their ethnic churches throughout Eastern Europe and the Middle East. Emigres from those countries to the United States brought with them their ethnic churches.

With the communist takeover of Russia after World War I, relationships of Russian Orthodox congregations in this country with the patriarchate in Moscow became extremely problematic and the group split into three factions. In 1970 the largest faction secured from the Moscow patriarchate formal recognition as the indigenous church of Orthodox Christianity in America, although other Orthodox groups contest that status.

Although Russian-Americans form the core of the OCA, the present leadership is seeking to guide the church into the mainstream of American life. Church services in English are commonplace and the church stresses an evangelism program aimed at unchurched Americans, irrespective of background.

The church's council meeting in Detroit changed church rules to permit women to serve as delegates to future councils.

A resolution on human rights sharply criticized the Soviet Union for the persecution of Christians there and called on all governments to live up to the guarantees of religious freedom contained in the Helsinki Agreement.

The church's Council of Bishops also issued a statement critical of the Department of Justice for the "tragic injustice" it said Romanian Orthodox Archbishop Valerian Trifa suffered becase of delays in his trial. Trifa, who immigrated to this county in 1950, was accused of lying about his alleged complicity in the deaths of 4,000 Romanian Jews when he was a leader of the Nazi-oriented Iron Guard in 1941. The Justice Department filed charges against him five years ago. In August, just seven weeks before a scheduled trial date, Trifa formally relinquished his citizenship, citing heavy costs of time and money for the anticipated legal battle to preserve it.